Malvertisement evolution - Perform three checks before forwarding the victim to a malicious website.

1. The user agent must be mobile-specific - Sites being targeted by the malware are all optimized to be viewed primarily via mobile device.
2. Battery level must be between 20 and 76 percent - To avoid detection from scanners
3. HTTP referrer must be specified - avoid detection by known security vendors

https://www.scmagazine.com/home/security-news/assault-and-battery-malvertising-campaign-checks-user-device-charge-as-anti-detection-technique/